Officially, I don't think Asus supports the server OS for this MB, but chances are that if it supports Win7 x64 then it should be fine on 2K8R2. Do I need to go though and change the OS id in the INI file in order to get it to install the Win7 drivers?
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Chances are it will install, but you might have some driver issue in the Device Manager and need to go hunting for supported drivers. Often going to the OEM site will offer the missing drivers if any.